Curved extension drill



Nov. 1, 1960 R. L. MGNUTT cuRvED EXTENSION DRILL Filed Aug. 2s, 1957 RALPH L. Mc/VUTT INVENTOR.

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TTORNE Y Unite States This invention relates to boring devices and has reference to a curved extension drill for boring holes in otherwise inaccessible places, such as in plates between inner and outer wall surfaces when installing electrical wiring or plumbing.

An object of the invention is to provide an extension drill which requires only `a relatively small hole in a wall surface for its successful operation.

Another object of the invention is to provide guide means for locating the bit of a curved extension drill when the bit end thereof is received between two wall surfaces.

A further object of the invention is to provide a curved extension drill having an outer sleeve which is stationary during the drilling operation and whereby the user of the drill may hold the sleeve with one hand for maintaining the direction of the hole being drilled.

These and other objects will become apparent from the following description and acompanying drawing, wherein:

Figure 'l is a broken vertical sectional view of a wall showing a combined elevational and sectional view of a preferred form of the invention positioned therein preparatory to drilling a hole through a lower wall plate and a subfloor.

Figure 2 is an enlarged broken vvertical sectional view of the lower end of the curved extension drill illustrated in Figure 1.

.Figure 3 is an enlarged vertical sectional View of the upper end of the curved extension drill illustrated in Figure l.

The wall shown in Figure 1 includes inner and outer wall surfaces and 11, a lower wall plate 12, a subfloor 13, a sill 14, and a sill plate 15, the latter being mounted on concrete foundation 16. A typical use for the present invention is to drill a hole 17 through the lower wall plate 12 and subfloor 13 for installing electrical wiring which will extend to an electric outlet box, not shown, in an opening 18 in the inner wall 10. The size of the opening 18 is only slightly larger than the outlet box to be installed.

The form of the invention shown includes a tubular outer sleeve 19 which is bent, as at a, intermediate its ends, a bit 20 within its lower straight portion, an inner sleeve bearing 21 slidably mounted in the upper straight portion, and a ilexible shaft 22 connecting the bit and the slidable bearing. The straight portions of the sleeve 19 deiine an included angle of approximately 135 The lower end of the outer sleeve 19 is notched, as at 23, for chip clearance. The bit shank 24 is rotatably and slidably received in a bearing 25 located in the lower end of the sleeve 19 immediately above the recess 23. As shown in Figure 2, the bearing 25 is detachably secured in place by means of a set screw 26 threadedly engaged in and extending through the sleeve 19 and into a recess 27 in the side of the bearing 25. The shank 24 of the bit 20 is connected with the lower end of the flexible shaft 22 by means of a set screw 28 threadedly positioned through "arent the side of a tubular adapter 29, the outside diameter of said adapter being slightly less than the inside diameter of said sleeve, and which set screw extends into a recess 30 in the upper end of said bit shank which is slidably received within said tubular adapter. The set screw 28 is accessible through an opening 31 in the side of the sleeve 22.

The upper end of the ilexible shaft 22 is connected with la straight shaft 32 which extends through and is rotatable in the slidable bearing sleeve 21. The connection between the exible shaft 22 and the straight shaft 32 is by means of an adapter 33 of a construction like that described in connection with adapter 29.

The upper end of the slidable sleeve bearing 21 is shouldered, as at 34, to limit the downward movement of the outer sleeve 1.9. The upper extending end of the shaft 32 is engaged in the chuck 35 of an electric hand drill 36. A collar 37 is mounted on the extending end of the shaft 32 immediately above the sleeve shoulder 34, and which collar is held in place by means of a set screw 38.

In operation, the bit end of the described extension drill is inserted through the opening 18 in the inner Wall 10 and placed on the surface of the plate 12 to be drilled. In this position, the inner sleeve bearing 21 is outwardly extended, and at which time the outer sleeve 19 is manually held in operating position. Pressure is applied to the hand drill 36 as the bit 20 drills the hole '17, and at which time the entire inner mechanism of the described extensiou drill, with the exception of the lower bearing 25, moves downwardly to complete the hole. It is pointed out that there is no downward movement of the bent outer sleeve; thus, the opening 18 may be relatively small.

The invention is not limited to the exemplary construction herein shown and described, but may be made in various ways within the scope of the appended claims.

What is claimed is:

1. A portable hand drill extension for drilling a perpendicular hole in a horizontal wall plate between inner and outer walls, said drill extension comprising a rigid tube having a vertical straight lower end when in operating position and curved thereabove, a drilling assembly longitudinally slidable within said tube, said drilling assembly comprising a exible shaft within said tube, a wood bit having a shank, said bit being adapted to be received within and extend from the straight lower end of said tube, a cylindrical connector within the straight lower end of said tube and connecting one end of said llexible shaft with the shank of said bit, the outside dia meter of said connector being of a size to rotate and slidably engage the lower end of said tube, a rigid shaft connected with the upper end of said iexible shaft and extending outwardly of the upper end of said tube, said rigid shaft being of a size to be engaged by the chuck of an electric hand drill, and means within said tube limiting the longitudinal movement of said drilling assembly in said tube.

2. A portable hand drill extension for drilling a perpendicular hole in a horizontal wall plate between inner and outer walls, said drill extension comprising a rigid tube having a vertical straight lower end when in operating position and curved thereabove, a drilling assembly longitudinally slidable within said tube, said drilling assembly comprising a tlexible shaft within said tube, a wood bit having a shank, said bit being adapted to be received within and extend from the straight lower end of said tube, a cylindrical connector within the straight lower end of said tube and connecting one end of said flexible shaft with the shank of said bit, the outside diameter of said connector being of a size to rotate and slidably engage the lower end of said tube, a rigid shaft connected with the upper end of said flexible shaft and extending outwardly of the upper end of said tube, said rigid shaft being of a size to be engaged by the chuck of an electric hand drill, and bearings mounted in upper rand lower ends of tube, the bearing in the lower end of said tube being at the lower end of the said straight lower end and slidably engaging the shank of said bit, and the upper said bearing being slidably mounted in the upper end of Said tube and rotatably engaging said rigid shaft.

3. A portable hand drill extension for drilling a perpendicular hole in a horizontal wall plate between inner and outer walls, said drill extension comprising a rigid tube having a vertical straight lower end when in operating position and curved between the ends thereof, the upper and lower ends of said tube being disposed at an angle of substantially 135, a drilling assembly longitudinally slidable within said tube, said drilling assembly comprising a exible shaft within said tube, a wood bit having a shank, said bit being ladapted to be received within and extend from the straight lower end of said tube, a cylindrical connector within the straight lower end of said tube and connecting one end of said exible shaft with the shank of said bit, the outside diameter of said connector being of a size to rotate and slidably engage l the lower end of said tube, a rigid shaft connected with the upper end of said iexible shaft and extending outwardly of the upper `end of said tube, said rigid shaft being of a size to be engaged by the chuck of an electric hand drill, and means within said tube limiting the longitudinal movement of said drilling assembly in said tube.

References Cited in the tile of this patent UNITED STATES PATENTS FOREIGN PATENTS Germany Nov. 24, 1930 Germany Dec. 8, 1952 

